<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>悬停效果示例</title>
    <style>
        .red1{
            width: 200px;
            height: 100px;
            background-color: red;
            transition: background-color 0.3s ease;
        }
        .red1:hover{
            background-color: #ff9fb9;
        }
    </style>
</head>
<body>
    <div class="red1">123</div>
</body>
</html>